try
let argv = Array.of_list ("make"::args) in
pid := Unix.create_process "make" argv Unix.stdin out_w err_w;
-let ch = open_out "/tmp/pippo" in output_string ch (String.concat " " ("make"::(Array.to_list argv)) ^ "\n"); flush ch; close_out ch;
Unix.close out_w;
Unix.close err_w;
let buf = String.create 1024 in